1. Field of the Invention
The present invention generally relates to recording apparatuses and, more particularly, to a recording apparatus, such as an inkjet recording apparatus, which ejects droplets of a liquid onto an intermediate transfer member to form a visible image and transfers the visible image to a recording medium such as a sheet of recording paper.
2. Description of the Related Art
In the inkjet recording method in which an ink image is formed by projecting ink droplets in accordance with image signals, high quality paper must be used as a recording medium so that the ink does not run on or penetrate into the recording medium. In order to solve the problem with respect to the ink running on the recording medium, the following methods have been suggested.
1) Japanese Laid-Open Patent Applications No. 6-92009 and No. 6-92010 disclose a method in which an ink curing agent is applied onto ink droplets at the same time or immediately before or after the ink droplets are applied to a sheet of recording paper. That is, in order to prevent the ink from running, droplets of the ink curing liquid are applied to a position on a sheet of regular paper, to which position the ink droplets are applied, at the same time or immediately before or after the ink droplets are applied to that position. This method requires an additional mechanism for applying droplets of the ink curing liquid. Additionally, there is a drawback in that the recording time interval is longer than the recording time interval of the conventional inkjet recording method due to the curing time of the ink curing liquid.
2) Japanese Laid-Open Patent Application No. 5-96720 discloses a fixing method in which an ink image is provided on a sheet of recording paper after a material which reduces running of ink is applied to the surface of the recording paper, and thereafter the ink image is fixed to the sheet of recording paper. That is, particles made of the material, which reduce running of ink, are previously applied to the surface of the sheet of regular paper, and an ink image imagine is fixed to the layer of the particles. After the ink image is fixed, the particles also become fixed to the sheet of recording paper. The material of the particles used in this method dissolves into the ink, and, thereby, the particles may react with an ink solvent such as water or oil on the sheet of recording paper. Thus, there is a problem in the stability of the ink image during storage of the recording paper after the ink image is recorded.
3) Japanese Laid-Open Patent Application No. 7-89067 discloses a method performed by an inkjet recording apparatus using an intermediate transfer member. In this method, an ink image is formed on the intermediate transfer member, and the ink image is transferred onto a sheet of recording paper after the viscosity of the ink image is increased to an appropriate level so as to solve the problem with respect to running of ink on the recording paper. In this method, a surface active agent is previously applied to the surface of the intermediate transfer member so as to increase the wetting characteristic of the surface of the intermediate transfer member. Thus, it takes a considerable time interval for the ink image to achieve an appropriate viscosity. This may cause running of ink on the intermediate transfer member and also on the recording paper, and, thus, this method is not suitable for a high-speed recording. Especially, running of ink is more likely when the ink image is a large, high-intensity image. Accordingly, an inkjet recording apparatus using this method has a limit in increasing the recording speed due to the running of ink.
4) Japanese Laid-Open Patent Application No. 11-188858 discloses an inkjet recording method which solves the problems of the above-mentioned methods. In this method, a powder is applied to a recording medium before an ink image is formed on the recording medium. The material of the powder is soluble into or swollen by a solvent contained in the ink so that the viscosity of the ink droplets is increased, and the material does not react with the die or pigment contained in the ink. Since the ink droplets are applied onto the layer of the powder applied on the intermediate transfer member so as to form a visible image, a high quality ink image can be transferred onto a sheet of regular paper at a high speed without ink running.
The diameter of the powder particles used in this method is in the order of less than one micrometer. Accordingly, in order to apply a sufficient amount of powder to absorb the liquid contained in the ink droplets, the powder on the intermediate transfer member must be formed in a multi-layered structure in which each layer has a thickness corresponding to the diameter of the powder particles. If a sufficient amount of the liquid contained in the ink droplets is not absorbed by the powder, running of ink may occur when the ink image is transferred onto the recording paper. Thus, in order to apply the powder in a multi-layered structure with a uniform thickness, an extremely high accuracy is required of the mechanism applying the powder to the intermediate transfer member.
Additionally, when the powder remaining on the intermediate transfer member after the transfer of the ink image to the recording paper is not removed and is therefore reused in the subsequent image forming process by replenishing the necessary amount of powder by an application roller, the thickness of the powder layer tends to become uneven. Such unevenness in the thickness of the powder layer may cause the incomplete transfer of the ink image to the recording paper. Accordingly, in order to eliminate such a problem, the powder remaining on the intermediate transfer member is removed by a removing member such as a blade or a brush. However, normally, the amount of powder on the intermediate transfer member which is not used for forming an ink image is much larger than the amount of powder actually used for forming the ink image. Thereby, if the remaining powder is removed and not reused for the subsequent image forming process, there is a problem in that an extremely large amount of powder is consumed by the inkjet recording apparatus, resulting in an increase in the running cost of the inkjet recording apparatus. Accordingly, it is preferable to reuse the removed powder. However, there is a problem in that the removed powder contains both powder which has not been in contact with the ink droplets and powder which has been swollen due to contact with the ink droplets but has not been transferred to the recording paper. Therefore, the two kinds of powder must be separated from each other.
It is a general object of the present invention to provide an improved and useful recording apparatus and method in which the above-mentioned problems are eliminated.
A more specific object of the present invention is to provide a recording apparatus and method in which an appropriate amount of powder can be applied to an intermediate transfer member, the powder absorbing a liquid for forming an image to be transferred to a recording medium.
In order to achieve the above-mentioned objects, a setting agent is supplied to a carrier which then carries the setting agent, a part of the carrier having a plurality of depressions receiving the setting agent. The setting agent is made of a material in the form of powder that increases the viscosity of the droplets of the liquid by being dissolved into the liquid or absorbing the liquid. A visible image is formed on the setting agent carried by the carrier by applying the droplets of the liquid onto the setting agent. The visible image formed on the setting agent is transferred onto a recording medium.
According to the present invention, since the setting agent is placed in the depressions, the amount of the setting agent moved to the image forming position is determined by the size and number of the depressions. Thus, the amount of the setting agent moved to the image forming position can be easily set to an appropriate amount which is sufficient for increasing the viscosity of the droplets so that there is no running in the visible image formed by the droplets of the liquid whose viscosity is increased by the appropriate amount of the setting agent.
In one embodiment of the present invention, the setting agent is applied to an application roller having a surface on which the depressions are formed so that the setting agent is received by the depressions. Then, the setting agent carried by the depressions of the application roller is transferred onto an intermediate transfer member which carries and moves the setting agent to a position where the droplets of the liquid are applied.
In another embodiment of the present invention, the setting agent is applied to an intermediate transfer member having a surface on which the depressions are formed so that the setting agent is received by the depressions. Then, the setting agent is squeezed into the depressions of the intermediate transfer member.
Other objects, features and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings.